Viewsonic VP2030b

[Grubs]

Viewsonic VP2030b monitor.

It briefly went blink-blink-blink and then when turned off for the night would not turn on in the morning.

On pulling the boards I found two bad caps in the PSU almost instantly and new caps have been ordered from farnell.

220uf 25V left of the heatsink: 1x EKZE250ELL221MHB5D 25v 220uf KZE
470uf 16v on the right: United Chemi Con EKZE-160ELL471MH15

The two 1000 uf caps laying down on the right of the heatsink appear fine.

I see some pretty severe scorching of the PCB around the grey resistor (R56) to the left of the heatsink in the above shot.

I'm wondering if there are other components that are likely to have blown/fried.

I'm a dab-hand with a soldering iron and I can work a multi-meter but I dont have the knowledge/expertise to test components.

Q1: I know resistors are pretty robust - but should I be replacing this one? (value? type? farnell cat number?)

Q2: There is a diode above and in the same line as the resistor that looks like its either had a lot of current passing through it and its got hot..or its just been passively heatsinking from the hot resistor and also got hot - should I just aim to replace this also... how do I work out what type of diode it is..or can someone tell me?

Q3: Can I test the PSU without hooking it up to the monitor (ie like you can with computer PSU by bridging the ground (pins 3,4) and power-on pin (pin 8) of the 8-pin connector on the side of the PSU board (CN1)?

TIA for any help - pics below.

[Rtech]

Re: Viewsonic VP2030b

As soon as you plug in the mains, to the board,the PSU will work up to BUT not including the Inverter which powers the Backlights(CCFL's), so there is no need to connect anything to CN1, or CN2.So AFTER replacing the blown caps, you you can measure the DC voltages produced by the PSU, across the new caps and the laid down ones.
To check the diode,put your meter on diode test position and measure across it...one way should read between 0.5 and with leads reversed no reading.

[Grubs]

Re: Viewsonic VP2030b

Thanks for that. I removed the resistor and diode from the PCB for testing.

The diode appears to be a straight circuit - tester drops from 1.4V to zero in both directions. Marking say P6KE8.2A 5023 so Does this Farnell part look right? (Farnell had both P6KE8.2A and P6KE8.2A-E3/23 - the same?)

The picture below from another thread shows this resistor is marked 2.4 ohm but I'm measuring 50 Kohms

The markings on my resistor are mostly burnt off - I can make out the 2.4 and the ohm symbol ... I think it says 1WJ. Would this be 1 watt? About right for this size/shape? Is it a metal film resistor? -> This Farnell part?

If anyone with some clue can check the Farnell links above I'd appreciate it. I wonder if more is fried - this could be a lost cause

Picture from another thread below shows the markings on the 2.4ohm resistor if I'm reading it right!

[Rtech]

Re: Viewsonic VP2030b

Yes they both look good.2.4ohms is correct and metal film also as this type is more accurate than carbon...and 2.4 is not standard.
Good luck

[Rtech]

Re: Viewsonic VP2030b

Make sure you put the diode back in the same orientation the old one came out of.....shown by the white line on one end.

[Grubs]

Re: Viewsonic VP2030b

I've now accumulated all my caps for this repair but the resistors I ordered are of a different type. Can someone confirm if these are going to be suitable?

The markings I can read on the original are "2.4[ohm symbol]" and "1WJ" - thanks Rtech for confirming above.

I ordered 2.4ohm 1W metal film resistors - but they are a lot smaller and I'm wondering if I should have bought a different type or larger wattage (though appreciate they might just be a different design)?

I took the "1WJ" to mean 1W and Tollerance "J" = 5%..

The combination of small size (and thinner leads) of the new ones and the fact the old resistor burnt up is causing me to doubt the new smaller resistors are suitable... but perhaps the bad caps caused the burn and its not an issue?

Just go ahead and solder them in? ... or purchase something else?

(I guess if they burn out and act like a fuse I'll know something else is wrong!)
FWIW - the parts from Farnell have so far come from Malaysia, India, Japan,and USA in 4 separate deliveries.. amazing!

[lucky13]

Re: Viewsonic VP2030b

Grubs,

Have you inspected the caps on the Main board and the inverter board for bulging caps?

There had been many threads on this & VP2130B monitors on this forum.

[Grubs]

Re: Viewsonic VP2030b

Yes - thanks lucky. Thanks to the other posts on the forum I did find other bulging caps.

Last night I replaced:

3 x 180uf 35V on the inverter board

3 x 330uf 16V on the main board
1 x 1000uf 6.3V on the main board

1 x 220uf 25V on the power board
1 x 470uf 16V on the power board
1 x diode on the power board (shorted)
1 x 2.4ohm resistor on the power board (burnt)

All these caps were obviously bulging

The monitor is now working but I am hesitant about the small size of the 2.4ohm resistor that went to fix the power board (just because it didn't look the same). I found it too hard to test the monitor without mounting the boards into the carrier on the back of the screen...but after assembly I cant see the power board so I cant tell if its burning.

I have another two of these monitors that have not shown any symptoms yet... but I bought enough supplies to do the same on them.

Many thanks to www.badcaps.net and the VP2030b pioneers that came before me and posted!